Thank you for the replies.
Last year I was able to cook a Christmas cake whose recommended temperature was 140 but 120 with fan assistance. Using the recipe's 30-45-minute extra-time margin, the cake was baked successfully.
With my planned mince pies, however, this looks like a whole new ball...
I have an electric oven which, although its rated highest temperature is 240 degrees Celsius, can only manage about 120 in reality.
I would like to know if there is any kind of conversion table I can use to adjust cooking times for lower temperatures.
For example, if something needs 20 minutes...